Optical transmission of liquid-crystal field-effect cells

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Abstract
The relationships between the optical transfer characteristics of twisted‐nematic liquid‐crystal devices and the material and cell parameters were investigated. The dependence of transmission on wavelength, birefringence, cell thickness, and surface alignment was measured as functions of light direction and operating conditions. The experimental results were confirmed by calculations of the transmission using Berreman’s numerical procedure for anisotropic media. The angle over which good contrast is observed increases with increasing wavelength and decreasing cell thickness and birefringence. This is accompanied by a decreasing value of optical threshold. The most uniform response and widest viewing angle is obtained with materials of small birefringence in cells with near‐planar alignment.